Cu 2 ZnSnSe 4 (CZTSe) thin films are grown by coevaporation. Composition depth profiles reveal that a Zn rich phase is present at the CZTSe/Mo interface. Raman measurements on the as grown films are used to study the near surface region and the CZTSe/Mo interface, after mechanically removing the thin film from the Mo coated glass. These measurements provide direct experimental evidence of the formation of a ZnSe phase at the CZTSe/Mo interface. While the Raman spectra at the surface region are dominated by CZTSe modes, those measured at the CZTSe/Mo interface are dominated by ZnSe and MoSe2 modes.

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As highlighted by recent conversion efficiency records, passivating contacts are keys to fully exploit the potential of crystalline silicon as a light absorbing semiconductor. Prime passivating contact technologies include a-Si/c-Si silicon heterojunctions and high temperature tunnel oxide/polysilicon-based contacts. The first has the advantage of a simple fabrication process, but it is incompatible with standard metallization processes and bulk semiconductor defect treatments which take place at temperature > 800°C. The second relies on a buried junction or dopant profile near the tunnel oxide, and requires process times of several minutes at high temperature. In this paper, we solve the scientific question to know whether such a dopant profiles, with the possible the presence of nano-holes, is required to make an efficient contact when using a tunnel oxide. We show that, by leveraging the versatility of plasma deposition processes, it is possible to realize Si-based thin-film doped layers that withstand a short annealing at high temperature (> 800 for typ 10 s, called "firing"), passivate the c-Si interface and foster collection of photo-generated charge carriers by inducing a strong electric field at the Si-surface near the interface with SiOx. The contact has a high-compatibility with existing industrial process: a plasma deposition of a thin-film layer at the rear side followed by a rapid thermal treatment ("firing"), an essential process for metallization formation of industrial cells. With the developed technology, we fabricated proof-of-concept p-type solar cells with conversion efficiency up to 21.9%.

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